中国南部亚热带森林地表植被动态变化

系统研究了南方5个亚热带森林生态系统地表植被的动态变化情况.研究方法是:在每个研究区域内,按照地形梯度分别布设50个1m2 的样方,记录样方内所有物种的频度及相关的环境变量,5个研究区域共设250个样方,每个样方分别调查两次.通过单元及多元统计方法分析表明:维管植物物种频度在一个区域明显下降,另二个区域显著增加;苔藓物种频度在一个区域有明显下降,另一个区域明显增加;苔藓物种数量在3个区域显著增加,另二个区域显著下降;维管植物物种数量显著增加在二个区域;物种组成沿着第一个植被梯度轴DCA 1没有显著变化,沿着第二个植被梯度轴DCA 2在二个区域有显著变化.综合分析表明,苔藓对气候变化及其波动反映敏感,是较好的气候变化及气候波动生物指示因子,而管植物数量及频度的变化没有明显证据显示与土壤酸化和大气污染有紧密关系.

Changes in forest ground vegetation in subtropical forest ecosystems, Southern China

The main aim is to identify changes in forest ground vegetation in five study areas in southern Chinese forests during the first two years after establishment. Abundances of all species were recorded in 50 marked 1m2 vegetation plots in each of five study areas, situated in forests dominated by subtropical broadleaved and coniferous trees. All 250 plots were analysed twice in 2000-2002 and two years later (2002-2004). Species abundance was analysed by univariate and multivariate statistical methods. Two-year changes in single-species abundances, species number and species composition were tested. Results showed that vascular plant species decreased significantly in abundance in one area and increased significantly in two areas, whereas bryophyte species decreased significantly in abundance in one area and increased significantly in another area. The number of bryophyte species increased significantly in three areas and decreased significantly in two areas, whereas the number of vascular plant species increased significantly in two areas. Significant change in species composition along the second most important vegetation gradient (DCA2) was observed in two areas. The patterns of changes in bryophytes can be explained by climatic fluctuations, substantiating that the bryophytes are good indicators of biotic effects of climatic change. The increase in the abundance and numbers of vascular plant species in two areas is most likely due to seasonal variation and more favourable climatic growth conditions the second and third years, compared with the first year of analysis. No clear indications have been found of changes in vascular plant species that may be linked to soil acidification or direct effects of air pollutants.